Apparatus for forming a clinched seam



A ril 5, 1966 w. c. BROOKSON APPARATUS FOR FORMING A CLINCHED SEAMOriginal Filed Aug. 2. 1960 IN V EN TOR. W/Z 1 /4M (IV/4ft 5 BAOO AGENTUnited States Patent APPARATUS FOR FORMING A CLINCHED SEAM WilliamCharles Brookson, Hamilton, ()ntario, Canada, assignor to American CanCompany, New York, N.Y., a corporation of New Jersey Application Oct. 4,1961, Ser. No. 146,685, now Patent No. 3,157,398, dated Nov. 17, 1964,which is a division of application Ser. No. 46,913, Aug. 2, 1960, nowPatent No. 3,053,409, dated Sept. 11, 1962. Divided and this applicationDec. 11, 1964, Ser. No. 424,160

2 Claims. (Cl. 29121) This is a division of application Serial No.146,685 filed October 4, 1961, now Patent No. 3,157,398, issued November17, 1964 which is a division of application Serial No. 46,913 filedAugust 2, 1960, now Patent No. 3,053,409, issued September 11, 1962.

The present invention relates to the clinching of an end onto can bodiesto facilitate the vacuumizing of double seamed cans prior to the finaldouble seaming operation, and has particular reference to the formationof a clinched seam wherein conventional can body and end flanges arerolled together to interlock them in such manner as to positivelyprevent the lining compound which is carried on the end flange fromseating on the body flange to hermetically seal off the interior of thecan.

In the canning of comminuted products such as powdered milk, groundcoffee and the like, it is necessary to remove as much as possible ofthe air which is entrapped within the can and the product containedtherein prior to the final double seaming operation in order to preventsubsequent deterioration of the product by oxidation. Removal of thisair is usually effected by placing the filled but unsealed can in aclosed chamber and subjecting the chamber to a high vacuum in order toevacuate the interior of the can.

In such vacuumizing operation, vacuums as high as 29.8 inches of mercurymay be employed. Since automatic equipment is usually employed, the timeduring which the evacuating process can be effected is necessarilylimited and the vacuum is created in the vacuum chamher in a relativelyshort time. As a result, there is a definite tendency for the air Withinthe can to be drawn from the can with great velocity, and the resultantoutrush of air from the can, unless controlled, frequently carries withit a portion of the comminuted product.

Obviously, removal of the product from the can interior in such manneris very undesirable. In order to prevent it, the usual practice is toapply the can cover to the can body prior to the time the can isinserted into the vacuumizing chamber, and to provide for passageways ineither the body or the cover through which the air may be withdrawn,these passageways being carefully dimensioned to limit and control therate of withdrawal of the air.

A generally used method of providing such passag way is to secure thecan cover to the can body in a preliminary seaming operation wherein thecan body and end flanges are rolled together to form an incomplete,nonhermetic seam which is referred to as a clinched seam, this seamingoperation being known as clinching operation. No particular difficultyis encountered in the formation of such seams when a low vacuum is beingdrawn, inasmuch as it is possible to use clinched seams which are quiteloose and which provide relatively large passageways for the flow ofair, since a low vacuum does not pull the air from the can interiorviolently enough to carry the product with it. Such loosely clin-ichedseams can be easily formed without danger of creating a hermetic seamthrough which the air cannot pass. However, when very high vacuums arebeing utilized, the clinched seam inust be relatively tight in order toprevent 3,243,865 Patented Apr. 5, 1966 the air from being pulled fromthe can too rapidly, and there is the ever present possibility that intight seams the end lining compound will seat on the body flange andcreate a seal which is completely hermetic, or so close to beinghermetic as to effectively prevent the desired withdrawal of the airfrom the container interior.

A relatively tight clinched seam is also advantageous for use withpacking processes wherein the vacuum within the can is replaced by aninert gas such as carbon dioxide or nitrogen, while the can is still inthe closed chamber, for in such processes it is a common practice tointroduce the can into the outside atmosphere prior to the final seamingoperation, and a tight clinched seam is necessary to prevent the inertgas from spilling out of the can and being replaced, in part at least,by the outside air during the transfer of the can from the vacuumizingand gassing chamber to the closing machine. The tighter the clinchedseam, the less chance there is of such loss of inert gas.

The present invention provides a solution to this problem by providing aclinched seam construction which positively insures against seating ofthe end lining compound on the body flange to form a hermetic seal, andyet produces a seam which is tight enough to control the flow of airfrom the can when high vacuums are being used. This is effected bytightly rolling spaced portions of the seam together in such manner thatthe end lining compound carried by the cover in such spaced portions ispressed into engagement against the can body flange, thus locking thecover and can body together and holding them against untoward relativeaxial movement so that the seam does not open up to an undesirableextent when the can is subjected to external vacuum. However, the seam,between these tightly rolled portions, is formed with loosely rolledportions wherein the cover flange is lifted upwardly away from eliminatethe possibility of having the end lining compound in these portions seatupon the body flange. While in these loosely rolled areas there ismetal-to-metal contact between the contiguous portions of the can coverand can body, such contact is discontinuous because of the inherentirregularities in the metal of these parts and is not effective inpreventing the passage of the air through these portions of the seam.

The clinched seam of the instant invention is formed by a speciallyprofiled, generally circular clinching roll which is provided with anendless clinching groove which is radially non-concentric with theclinching roll axis in order to create the alternate loose and tightseam portions, and which, axially of the roll is of wavy or sinuousconfiguration so that it is provided with a series of high spots whichactually lift the cover flange upwardly away from the body flange in theloose seam portions. As a result of the fact that the cover flange islifted away from the body in the loosely formed seam portions, there issubstantially no chance of having the end lining compound in such areasseat on the body flange and passage of air through the seam is alwaysinsured.

An object of the invention therefore is the provision of a clinched seamconstruction wherein the seam is formed With alternately loosely andtightly rolled portions in such manner that the seating of the endlining compound in the loosely rolled portion is effectively prevented.

Another object of the invention is the provision of such a clinched seamwhich can be formed from conventional can bodies and ends, and whichrequires no special body or end configurations.

Yet another object is the provision of a tightly clinched seam which iseffective to prevent the loss of gas from a clinched can after the gasfilled clinched can is passed into the body flange in order topositively I the outside atmosphere preparatory to the final seamingoperation.

Another object of the invention is the provision of a method of formingsuch a clinched seam.

Still another object is the provision of a specially constructed seamingroll for effecting the formation of such seams.

Numerous other objects and advantages of the invention will be apparentas it is better understood from the following description, which, takenin connection with the accompanying drawings, discloses a preferredembodiment thereof.

Referring to the drawings:

FIGURE 1 is a side elevation of a can having its cover secured in placein a clinched seam made according to the principles of the instantinvention, the view also showing in operative position relative to saidcan certain operating parts of a clinching machine, including aspecially profiled clinching roll which is designed to form the saidclinched seam;

FIG. 2 is a plan view of the clinched can and the clinching machineparts shown in FIG. 1;

FIG. 3 is a fragmentary vertical section on an enlarged scale takenthrough an upper peripheral portion of the can of FIGS. 1 and 2, butshowing the can end in assembled position on the can body preparatory tothe clinching operation;

FIG. 4 is a vertical section, on the same scale as FIG. 3, takensubstantially along the line 4-4 in FIG. 2, this view being takenthrough the loosely formed portion of the clinched scam, the view alsoincluding, in dot and dash lines, a vertical section taken through thecorresponding portion of the clinching roll which effects the formationof such loosely formed seam portion; and

FIG. 5 is a vertical section taken substantially along the line 5-5 inFIG. 2, this view being taken through a tightly rolled portion of theclinched seam and also showing in dot and dash lines a vertical sectiontaken through the corresponding portion of the clinching roll whichforms the tightly rolled seam portion.

As a preferred and exemplary embodiment of the instant invention thedrawings illustrate a can of the conventional double seamed varietywhich comprises a tubular can body 12 preferably formed with aconventional side seam 14 and having its lower end closed by a recessedbottom end member 16 which is secured thereto in a conventional doubleseam 18. The can 1%, after being filled with a suitable comminuted orpowdery product such as powdered milk (not shown), has applied to itsupper end a conventional cover member 28 of the type which is adapted tobe sealed to the body 12 in a conventional double seam.

In order to permit the formation of such a double seam, the can body 12is provided at its upper end with an outwardly extending annular flange22 which normally projects from the can body 12 in a generallyhorizontal plane, as best seen in FIG. 3. The cover member is providedwith a depressed center panel 24 which at its outer edge merges into anupwardly extending annular wall 26 which in the trade is referred to asa countersink wall. This countersink wall 26 in turn merges into anannular, outwardly extending cover flange 28 which at its outer edge isbent into a downwardly and inwardly extending curl 36. T he underside ofthe cover flange 23 carries an end lining compound 32 which normallycomprises a thin film of a rubbery material, which when compressedbetween the cover flange 28 and body flange 22 in the finished doubleseam (not shown), provides a hermetic seal.

When the cover member 28 is initially placed in position in the upperend of the can body 12, as best seen in FIG. 3, the end lining compound32 comes into loose contact with the upper surface of the body flange22. With these parts thus positioned, the filled can is fed into aclinching machine wherein the formation of the clinched seam of theinstant invention is effected. In such machine, the cover member 20 andcan body 12 are clamped together under pressure between a seaming chuck40, which is so shaped that it fits into the cover member 20 and engagesagainst the panel 24 and against the inner surface of the countersinkwall 26, and a lifter pad 42 which fits into the recessed bottom endmember 16.

After being thus clamped together, a clinching roll 44, made accordingto the principles of the instant invention, is moved radially of the canand brought into contact with the outer surface of the cover flange 28and curl 26 in order to reshape the cover flange 28 and body flange 22to form a clinched seam S, which tightly secures the cover member 29 inposition on the can body 12, but which is not hermetically sealed andthus permits the passage of air from the interior of the can when theclinched can is subsequently introduced into a vacuumizing chamber (notshown).

The clinching roll 44 is carried by a shaft 46 and is mounted for axialrotation, being either positively driven by the shaft 46 or idly affixedthereto. Suitable means are provided to effect a relativecircumferential movement of the rotating clinching roll 44 around theupper periphery of the can 10 and cover 2%! to thereby effect formationof the clinched seam S. This may be done either by moving the clinchingroll 44 bodily around the can 10 and cover 20, or by rotating the can 10and cover 20 on their own axes and maintaining a seaming roll shaft 46in a fixed position relative thereto.

As best seen in FIG. 1, the clinching roll 44 is formed with an upperannular shoulder 48, which extends inwardly over the cover flange 28,and a body portion 50 which is disposed immediately below said shoulder.An endless annular clinching groove 52 of special configuration is cutinto an outer periphery of the body portion 5%. This clinching groove 52throughout its length is uniform in vertical cross-sectional contour asbest seen in FIGS. 4 and 5, but is generally sinuous or wavy as viewedin side elevation (see FIG. 1) and is formed with a plurality of evenlyspaced high portions 54 which are offset upwardly relative to theintervening low portions 56. The distance of otfset is comparativelysmall, and may be in the nature of .025, although this figure may bevaried somewhat on either side and still produce the desired results.

In addition to its serpentine configuration, the groove 52 is irregularin that it is not concentric with the axis of the seaming roll44, but ispreferably formed of a plurality (-here shown as three) of eccentricgroove segments 58 each of which extends around the clinching roll 44,thus forming what in effect is a three lobed groove. The eccentricity ofthe segments 58 is, however, comparatively minor so that they mergesmoothly into each other at their ends at points which are designated bythe letter B, the groove 52 at such points being at its maximum distancefrom the axis of the clinching roll 44 (as best seen in FIG. 2). Thetotal eccentricity of the segments 58 is not critical, but as example,there may be radial variations of approximately .055" in the groove 52of a roll wherein the diameter of the body portion 59 is approximately1.977". As best seen in FIG. 1, the body portion 59 is not actuallycircular but has a circumferential contour which is substantiallyparallel to the contour of the clinching groove 52, being formed ofthree eccentric segments which merge smoothly intoeach other.

The clinching groove 52 is formed so that there is a definiterelationship between its eccentricity and its sinuosity, the low spots56 of the groove 52 coinciding with the points E of greatest radiallength, and the high spots 54 lying midway between the points E andcoinciding with those portions of the groove 52 having the shortestradial length.

When the clinching roll 44 is moved inwardly against the flange 28 ofthe cover member 20, the climbing groove 52 reshapes this flange 28 toroll it downwardly and inwardly beneath the can body flange 22, and thismovement of the cover flanges 28 in turn bends the body flange 22downwardly and inwardly, the result being that these flanges are rolledtogether and interlocked to form the clinched seam S of the instantinvention.

Because of the unusual configuration of the seaming groove 52, thisclinched seam is not formed of uniform tightness, but rather comprises aseries of loosely clinched portions, which will be hereinafter referredto by the letter L, and a series of tightly clinched portions which willhereinafter be referred to by the letter T, the portions L and T merginginto each other smoothly and evenly, as best seen in FIG, 1.

At the tightly clinched portions T, the can body and end flanges 22, 28are tightly rolled together in such manner that the end lining compound32 seats upon the body flange 22 as clearly seen in FIG. 5, thuselfecting a substantially hermetic seal at these portions.

The tight seam portions T are formed by the portions E of the clinchinggroove 52, because at such points the clinching groove 52 has itsgreatest radial length, and thus extends farthest towards the axis ofthe can body 12 and cover 20. Also, the portions E coincide with the lowspots 56 of the groove 52 and the combination of these two factorseffects the maximum reshaping of the can parts and in effect gives thetight seam portions T a contour which closely approximates that of afull first operation seam.

Laterally of the tight seam portions T, however, the cover flange 28 isgradually lifted upwardly away from the body flange 22 by the high spots54 of the clinching groove 52, and in addition, is rolled less tightlyin a lateral direction as the portions 54 of the clinching groove 52become operative. As a result, the lining compound 32 in such seamportions is positively lifted out of contact with the body flange 22,and is prevented from seating thereon. As seen in FIG. 4 the body flange22 may be reshaped slightly, even in the loose seam portions L, but isnevertheless maintained out of contact with the lining compound 28.

Thus, when the clinched can is placed in the vacuumizing chamber andsubjected to external vacuum, the air within the can passes easily andreadily through the loose seam portions L and the desired vacuum withinthe can is quickly obtained, despite the fact that metalto-metal contactbetween the can body and cover may be present in such loosely rolledportions.

It will be clear that the invention is not limited to a clinching rollwherein the lobes which form the tight seam portions T are formed byeccentric segments in the manner shown, but that the lobes may be formedin any manner, as long as the groove contains portions of ditferentradial lengths. It will also be clear that the invention is not limitedto a three lobed clinching groove, but that a groove having one or morelobes will effect alternate loose and tight seam portions, the frequencyand spacing between such portions however, being determined by thenumber of lobes used. In every construction, however,

the low portions of the clinching groove will concide with the groovelobes, so that these portions of the groove will produce tight seamportions.

After the air has thus been removed from the can, it is necessary todissipate the vacuum within the can in order to prevent its replacementby the external air if the clinched can is to be introduced into theoutside atmos phere prior to the final seaming operation. In such event,the vacuum in the chamber is replaced by an inert gas such as nitrogenor carbon dioxide which is held at substantially atmospheric pressure.Because of the high vacuum within the can, such inert gas passes throughthe loose seam portions L and enters the can until it establishes asubstantially atmospheric pressure therewithin. Thereafter, the clinchedgassed can may be introduced into the external atmosphere, and then fedinto a closing machine wherein the final double seam is formed in theconventional manner. Because of the fact that the gas pressure Within issubstantially in balance with the atmospheric pressure, and because thepassageways in the loosely seam portions L are restricted by themetal-to-metal contact in such areas, there is substantially no tendencyfor the gas in the can to be replaced by the external air during thetime the can is being transferred from the chamber to the closingmachine, and thus the oxygen content of the finally seamed can is heldto a minimum.

It is thought that the invention and many of its attendant advantageswill be understood from the foregoing description, and it will beapparent that various changes may be made in the form, construction andarrangement of the parts and in the steps of the method described andtheir order of accomplishment without departing from the spirit andscope of the invention or sacrificing all of its material advantages,the form hereinbefore described being merely a preferred embodimentthereof.

I claim:

1. A clinching roll, comprising a body having an axis, and an endlessclinching groove of substantially uniform cross-section formed in theperiphery of said body, said clinching groove having an axially sinuousconfiguration comprising a plurality of gently merging high and lowportions, and being formed with a plurality of lobes, each of said lobescoinciding with a said low groove portion.

2. A clinching roll comprising a body mounted for rotation about itsaxis, and an axially wavy clinching groove of uniform cross-sectionformed in the periphery of said body, said clinching groove comprising aplurality of gently merging high and low portions and being formed witha plurality of non-concentric radial portions which merge smoothiy attheir ends to form a plurality of lobes which coincide with the lowportions of the groove.

References Cited by the Examiner UNITED STATES PATENTS 109,163 11/1870Whitney 7453 2,802,366 8/1957 Borner 74-230.24

CHARLES W. LANI-IAM, Primary Examiner,

1. A CLINCHING ROLL, COMPRISING A BODY HAVING AN AXIS, AND AN ENDLESSCLINCHING GROOVE OF SUBSTANTIALLY UNIFORM CROSS-SECTION FORMED IN THEPERIPHERY OF SAID BODY, SAID CLINCHING GROOVE HAVING AN AXIALLY SINUOUSCONFIGURATION COMPRISING A PLURALITY OF GENTLY MERGING HIGH AND LOWPORTIONS, AND BEING FORMED WITH A PLURALITY OF LOBES, EACH OF SAID LOBESCOINCIDING WITH A SAID LOW GROOVE PORTION.